1. Technical Field
Various exemplary implementations relate generally to an electronic device and an operating method thereof and, more particularly, to a semiconductor device and a method of operating the same.
2. Related Art
As the need for a mobile phone, a mobile memory device, a digital camera, etc. increases, the need for the nonvolatile memory device used as the memory device for such products is also on the rise. Among the nonvolatile memory device, a NAND flash memory device is mainly used as a data storing device.
The NAND flash memory device may be categorized into a 2-dimensional semiconductor device having a cell string vertically formed on the semiconductor substrate and a 3-dimensional semiconductor device having a cell string vertically formed on the semiconductor substrate.
The 3-dimensional semiconductor device is a memory device devised in order to overcome the limit of degree of integration in 2-dimensional semiconductor devices and includes a plurality of cell strings vertically formed on the semiconductor substrate. The cell strings include a drain selection transistor, memory cells and a source selection transistor connected in series between a bit line and a source line.
Meanwhile, the threshold voltage of the memory cells connected adjacent to the drain selection transistor of the 3-dimensional semiconductor device may vary at the time of the program and read operations due to the resistance adjacent to the source line, which may have a negative impact on the reliability of the 3-dimensional semiconductor device.